Digital Commons Network^™

Development Of Tripodal And Bipodal Ligand Frameworks And First-Row Transition Metal Reagents For Selective C-N Bond Construction Methodologies, Anshika Kalra

Doctoral Dissertations

"We present a family of anionic Mn(II) reagents supported by trisphenylamido- amlne frameworks that offer guidance with regards to ligand selection for developing C—N bond construction methodologies (extensively used in the synthesis of petrochemicals, household chemicals) through nitrene- transfer chemistry. We subsequently extend the study to include the corresponding Fe(II), Co(II), and Ni(II) reagents, to gain insights in their comparative reactivity/selectivity patterns. Attenuated levels of electrophilicity of anionic complexes proved to be more suitable for discriminating aromatic from aliphatic olefins for aziridination purposes, especially for Mn(II) complexes. However, in the case of Co(II) reagents, we observe that additional stereoelectronic parameters …

Improving The Data Quality In Gravitation-Wave Detectors By Mitigating Transient Noise Artifacts, Kentaro Mogushi

Doctoral Dissertations

“The existence of gravitational waves (GWs), small perturbations in spacetime produced by accelerating massive objects was first predicted in 1916 as solutions of Einstein’s Theory of General Relativity (Einstein, 1916). Detecting and analyzing GWs produced by sources allows us to probe astrophysical phenomena.

The era of GW astronomy began from the first direct detection of the coalescence of a binary black hole in 2015 by the collaboration of the advanced Laser Interferometer Gravitational-wave Observatory (LIGO) (Aasi et al., 2015) and advanced Virgo (Abbott et al., 2016a). Since 2015, LIGO-Virgo detected about 50 confident transient events of GW signals (Abbott et …

Multi-Fidelity Modeling For Aerothermal Analysis Of Deployable Planetary Entry Technologies, Mario J. Santos

Doctoral Dissertations

“NASA is developing deployable entry technologies in the form of the Hypersonic Inflatable Aerodynamic Decelerator (HIAD) and the Adaptable Deployable Entry Technology (ADEPT) vehicles to support human exploration of Mars. To ensure that these technologies are reliable under uncertain entry conditions and extreme aerothermal environments, uncertainty quantification must be integrated into the design process which typically requires large number of high-fidelity computational fluid dynamics (CFD) simulations with prohibitively high computational cost. To address this challenge, construction of multi-fidelity aerothermal response predictions which combine low-fidelity correlations with fewer high-fidelity CFD models in a way that produces highly accurate surrogates with reduced …

Mantle Flow Systems Associated With Slab Subduction And Absolute Plate Motion In Alaska Constrained By Shear Wave Splitting Analyses, Yuchen Yang

Doctoral Dissertations

"Alaska has long been recognized as a geologically complex region with a sharp contrast in tectonic activity between southern and northern Alaska. While the former is characterized by the subduction of the geometrically varying Pacific-Yakutat plate beneath the North American plate, the latter has a mostly stable cratonic setting. To investigate the mantle flow fields beneath Alaska and understand the influence of the subduction process on regional mantle dynamics, a total of 2790 pairs of well-defined teleseismic shear wave splitting (SWS) measurements recorded from 379 stations are obtained and analyzed. In addition, 247 pairs of SWS results from local earthquake …

Reveal Wind Loading Of Tornadoes And Hurricanes On Civil Structures Towards Hazard-Resistant Design, Ryan Honerkamp

Doctoral Dissertations

"Extreme winds impacting civil structures lead to death and destruction in all regions of the world. Specifically, tornadoes and hurricanes impact communities with severe devastation. On average, 1200 tornadoes occur in the United States every year. Tornadoes occur predominantly in the Central and Southeastern United States, accounting for an annual $1 billion in economic losses, 1500 injuries, and 90 deaths. The Joplin, MO Tornado in 2011 killed 161 people, injured more than 1000, destroyed more than 8000 structures, and caused $2.8 billion of property loss. Hurricanes occur predominantly on the United States East coast regions and along the coast of …

Information-Based Methods And Models For Particle Flow Filtering, Kari Catherine Ward

Doctoral Dissertations

"Recursive estimation methodologies, such as Kalman and Bayesian filters, typically require models of some kind to perform the estimation. This filtering process seeks to improve knowledge surrounding some quantities of interest, or states, over time by incorporation of imperfect observations. The models required pertain to the state dynamics, sensors from which measurements are obtained, and probabilistic models of the underlying stochastic processes. In addition to any number of necessary models, real-world application of a filter is normally accompanied by at least one, if not several, techniques to promote better performance. These methods vary in purpose from expanding the kinds of …

Semi-Empirical Modeling Of Liquid Carbon's Containerless Solidification, Philip C. Chrostoski

Doctoral Dissertations

“Elemental carbon has important structural diversity, ranging from nanotubes through graphite to diamond. Previous studies of micron-size core/rim carbon spheres extracted from primitive meteorites suggest they formed around such stars via the solidification of condensed carbon-vapor droplets, followed by gas-to-solid carbon coating to form the graphite rims. Similar core/rim particles result from the slow cooling of carbon vapor in the lab. The long-range carbon bond-order potential was used to computationally study liquid-like carbon in (1.8 g/cm³) periodic boundary (tiled-cube supercell) and containerless (isolated cluster) settings. Relaxations via conjugate-gradient and simulated-annealing nucleation and growth simulations using molecular dynamics were …

Robustness Against Attacks And Uncertainties In Smart Cyber-Physical Systems, Prithwiraj Roy

Doctoral Dissertations

Cyber-Physical Systems (CPS) are sensing, processing, and communicating platforms, embedded with physical devices that provide real-time monitoring and control. Security challenges in CPS necessitate solutions that are robust against attacks and uncertainties and provide a seamless operation, especially when used in real-time applications to monitor and secure critical infrastructures. CPS mainly consists of a physical component for sensing or monitoring and a cyber component for processing and communicating. The quality of interactions between physical and cyber systems has direct impacts on the system’s performance and reliability.

CPS plays a major role in smart services and applications within a smart living …

Investigating The Focusing Effect Of Charge Geometry With Computer Simulations, Witness Plates, And High-Speed Videography, Kelly Ray Williams

Doctoral Dissertations

"Scaled distance is used to calculate a safe standoff radius from the detonation of a known mass of an explosive. It has been shown that varying only the geometry of the charge significantly overdrives regions of the blast wave potentially resulting in hazardous overpressure levels at scaled distance safe radii. Pressure transducers are used to measure overpressure surrounding spherical, cylindrical, and cubic charges to determine if bridge waves were formed at the edges between flat sides as seen in published studies of cylindrical charges. In the fireball field a witness plate is used to evaluate radial energy distribution with a …

Cyclic Sequential Adsorption Desorption/Thermal-Catalytic Oxidation Of Volatile Organic Compounds: Material Development, Process Advancement/Improvement, And Numerical Modeling, Simulation And Optimization, Busuyi Ojo Adebayo

Doctoral Dissertations

"Volatile organic compounds (VOCs) are a group of useful organic chemicals but when emitted have contributed to air pollution. They affect human health, cause environmental degradation and contaminate our waters and soils, so they need to be controlled. When they exist in dilute concentrations, abatement becomes challenging, thus requiring advanced abatement methods, e.g., sequential adsorption desorption/thermal-catalytic oxidation process. The overall goal of this research was to abate dilute streams of VOCs via the process. The specific objectives were to 1) develop novel adsorbent/catalyst dual-function materials (DFMs) for the process, 2) improve the operability of a one-bed-one-column reactor configuration for the …

Investigating The Impact Of Rock Bridges On The Mechanical Behavior Of Jointed Rock Mass Using Lattice Spring-Based Synthetic Rock Mass (Ls-Srm) Approach, Mariam Salem Alebayat

Doctoral Dissertations

"Rock bridges were defined as a segment of intact rock that separates from discontinuities. Numerous studies are focused on developing methods to quantify their significance in rock mass strength and deformability behavior. This thesis aimed to enhance understanding of the effect of rock bridges on jointed rock masses in both laboratory and slope scales. For this purpose, the lattice spring base Synthetic Rock Mass (LS-SRM) method was adopted to conduct the numerical models, distinguished in computational efficiency, and simulates the brittle failure and roughness of discontinuities.

A robust approach was developed to optimize the calibration procedure to avoid the complex …

Prediction Intervals For Fractionally Integrated Time Series And Volatility Models, Rukman Ekanayake

Doctoral Dissertations

"The two of the main formulations for modeling long range dependence in volatilities associated with financial time series are fractionally integrated generalized autoregressive conditional heteroscedastic (FIGARCH) and hyperbolic generalized autoregressive conditional heteroscedastic (HYGARCH) models. The traditional methods of constructing prediction intervals for volatility models, either employ a Gaussian error assumption or are based on asymptotic theory. However, many empirical studies show that the distribution of errors exhibit leptokurtic behavior. Therefore, the traditional prediction intervals developed for conditional volatility models yield poor coverage. An alternative is to employ residual bootstrap-based prediction intervals. One goal of this dissertation research is to develop …

Analysis Of Turbulence Model Uncertainty For Canonical Flow Problems Including Shock Wave Boundary Layer Interaction Simulations, Aaron James Erb

Doctoral Dissertations

"The purpose of this research is to present results of an uncertainty and sensitivity analysis study of commonly used turbulence models in Reynolds-Averaged Navier-Stokes (RANS) codes due to the epistemic uncertainty in closure coefficients for a set of turbulence model validation cases that represent the structure of several canonical flow problems. The study focuses on the analysis of a 2D zero pressure gradient flat plate, a 2D wall mounted hump, and an axisymmetric shock wave boundary layer interaction, all of which are well documented on the NASA Langley Research Center Turbulence Modeling Resource website. The Spalart-Allmaras (SA), the Wilcox (2006) …

Modeling Time Series With Conditional Heteroscedastic Structure, Ratnayake Mudiyanselage Isuru Panduka Ratnayake

Doctoral Dissertations

"Models with a conditional heteroscedastic variance structure play a vital role in many applications, including modeling financial volatility. In this dissertation several existing formulations, motivated by the Generalized Autoregressive Conditional Heteroscedastic model, are further generalized to provide more effective modeling of price range data well as count data. First, the Conditional Autoregressive Range (CARR) model is generalized by introducing a composite range-based multiplicative component formulation named the Composite CARR model. This formulation enables a more effective modeling of the long and short-term volatility components present in price range data. It treats the long-term volatility as a stochastic component that in …

Investigation Of Packed Bed And Moving Bed Reactors With Benchmarking Using Advanced Measurement And Computational Techniques, Binbin Qi

Doctoral Dissertations

"Trickle bed reactors (TBR), as typical packed bed reactors (PBR), are widely used in various fields. Very limited information regarding the flow behaviors, hydrodynamic, and mathematical models in extrudate catalyst shapes, such as cylinders, trilobes, and quadrilobes, can be found in literatures because the major focus was on spherical shape. Therefore, a hybrid pressure drops and liquid holdup phenomenological model for extrudate catalyst shapes was developed based on two-phase volume averaged equations, which showed high accuracy against experimental data. The maldistribution and dynamic liquid holdup were investigated in quadrilobe catalyst using gamma-ray computed tomography. A pseudo-3D empirical model was developed …

A Fuzzy Clustering Methodology To Analyze Interfaces And Assess Integration Risks In Large-Scale Systems, Josh Henry Goldschmid

Doctoral Dissertations

“Interface analysis and integration risk assessment for a large-scale, complex system is a difficult systems engineering task, but critical to the success of engineering systems with extraordinary capabilities. When dealing with large-scale systems there is little time for data gathering and often the analysis can be overwhelmed by unknowns and sometimes important factors are not measurable because of the complexities of the interconnections within the system. This research examines the significance of interface analysis and management, identifies weaknesses in literature on risk assessment for a complex system, and exploits the benefits of soft computing approaches in the interface analysis in …

Enhanced Heavy Oil Recovery By Low Salinity Polymer Flood Combined With Microgel Treatment, Yang Zhao

Doctoral Dissertations

“Heavy oil resources account for a large portion of the total oil reserves around the world. The target heavy oil reservoir is located on Alaska’s North Slope (ANS). Advantages of low-salinity HPAM polymer (LSP) over high-salinity polymer (HSP) were demonstrated. LSP could recover more oil with 40% less polymer consumption. No additional oil was recovered by HSP after LSP flood. The first-ever polymer flood pilot on ANS showed remarkable success regarding water cut reduction, oil production increase, delayed breakthrough, and projected oil recovery improvement. Polymer alone was insufficient to achieve satisfactory recovery as the reservoirs were highly heterogeneous. Microgels could …

Multimodal Neuroscience Data Modeling And Inference, Sima Azizi

Doctoral Dissertations

“Mathematical models can be combined with deep learning and machine learning methods to provide new insights in neuroscience. The field of neuroscience is characterized by rich datasets that include fluid biomarkers, EEG signals, and advanced neuroimages. Recent advances in natural language processing have led to the opportunity to gain additional insights from rapidly growing text databases as well as electronic health records. In this research, we focus on applying computational intelligence methods to the analysis of three different complex data sources: blood levels of disease biomarkers, EEG signals from schizophrenic patients, and disease phenotypes encoded in electronic health records. First, …

Relating Detonation Parameters To The Detonation Synthesis Of Nanomaterials, Martin Langenderfer

Doctoral Dissertations

“This research investigates the physical and chemical processes that contribute to the detonation synthesis of silicon carbide nanoparticles. Bulk production of SiC nanoparticles through detonation is possible due to pressures achieved over 20 GPa and temperatures over 2000 K as well as quenching rates in excess of 13 billion K/second. These conditions catalyze reaction and bottom-up molecular growth while retaining particles < 100 nm in diameter. In this work, detonation synthesis of SiC was demonstrated by incorporation of polycarbosilane, an SiC precursor material, into an RDX/TNT explosive matrix prior to detonation. Detonation Synthesis of SiC was also accomplished by reacting elemental silicon with carbon liberated by the detonation of negatively oxygen balanced TNT. Hydrodynamic simulation of a 60:40 mass ratio RDX/TNT detonation created conditions thermodynamically suitable to produce cubic silicon carbide within the first 500 nanoseconds after the passage of the detonation wave while carbon remains chemically reactive for molecular formation. Simulations and experimental tests indicated that loading configuration and impedance mismatch of the precursor additives used in detonation synthesis results in conditions in the additives that exceed the accepted detonation pressure of the explosive by greater than three times. Finally, a full factorial experimental design showed increasing silicon concentration, reducing silicon size, and reducing oxygen balance by adjusting the ratio of RDX to TNT decreased the explosives detonation pressure by 20% and increased the soot yield and concentration of SiC observed in the detonation products by 82% and 442% respectively”--Abstract, page iv.

Experimental And Numerical Studies Of Novel Thermal Energy Storage Materials For Applications In Concrete And Energy Storage Systems, Wenyu Liao

Doctoral Dissertations

In this work, several types of novel thermal energy storage (TES) materials and composites are explored, and a series of numerical simulation models and experimental protocols are developed to evaluate the potentials of these materials to be applied in concrete, pavement, and thermal energy storage systems.

The first two types of novel TES materials/composites are at the micro-scale, which use micro diatomite (DE) and cenosphere (Ceno) as carriers of phase change material (PCM), respectively. The third type of novel TES material is at the macro-scale, utilizing lightweight sand (LWS) and lightweight coarse aggregate as carriers to load PCM. The last …

Teaching Critical Thinking Skills In A Chinese Immersion School, Pui Hung Helen Wong

Doctoral Dissertations

As a frontline teacher and administrator, I received feedback consistently from parents and students asking for a fun and effective method of instruction for Chinese language development in the US. This study explored the micro-level of how teachers in Chinese immersion schools create an environment to support development of students’ critical thinking skills while learning Chinese. I applied a qualitative approach to the research and designed a case study focused on answering the following research questions: How do teachers help their students to develop critical thinking skills when teaching in a Chinese immersion program? What are the challenges teachers have …

Pilipinx Radical Imagination: Healing And Visioning In Our Process Of Becoming, Anthony Abulencia Santa Ana

Doctoral Dissertations

There are estimated 10.4 million Filipinos living or working abroad primarily in the Middle East, Europe, Canada, and the United States searching for a better life for themselves and their families (Commission on Filipino Overseas, 2013). Due to economic motivation, assimilating to the host country's culture, values, and traditions is an act of survival. While the majority of the research has focused on the domestic workers’ experience, rarely has there been a study focusing on Filipinos in the diaspora positive contributions to the host country and their Pilipinx Radical Imagination. As a result, the purpose of this qualitative study is …

The Significance Of Jesuit Educational Institution In The Reconstruction Of Postcolonial And Post-Conflict East Timor, Plinio Do Rosario Gusmao Dosreis Martins

Doctoral Dissertations

East Timor, as a postcolonial and post-conflict country, has striven to develop its educational system for almost two decades after its independence in 2002. The current educational system with the Portuguese language as the medium of instruction has been a challenge for teachers and students in the teaching and learning process. The fact that teachers and students are still using Tétum as a supplementary language to explain and express ideas shows that the educators and learners are still struggling with Portuguese despite the efforts of East Timor government to bridge the language gap.

Teachers and students, conversely, acknowledge that the …

The Ignatian Pedagogical Paradigm As A Critical Theoretical Framework To Enhance Teachers' Professional Identity In Diverse Context, Lourdu Sunder Reddy Mummadi

Doctoral Dissertations

Several previous studies have revealed the need and necessity to enhance teachers’ perception of professional identity (PI) as it impacts their feeling of satisfaction and effectiveness in the classroom and their persistence in the profession (Moore & Hofman, 1988; Sanders et al., 1997; Hanushek, 2011). According to some scholars, teachers’ professional identity includes teachers’ understanding of themselves and the factors impacting their teaching (Beijaard et al., 2000; Sachs, 2005; Day, 2018). The danger is that if a teacher lacks self-knowledge, they may be influenced by unexamined beliefs, stereotypes, cultural myths, and, most importantly, fears that affect the ways they relate …

Effect Of Transcendental Meditation On The Social Emotional Well-Being Of Bilingual Teacher Leaders, Margaret Peterson

Doctoral Dissertations

Teaching is one of the most stressful professions in the human service industry (Curry & O’Brien, 2012; Fisher, 2011; Herman et al., 2018; Martin, et al., 2012; Montgomery & Rupp, 2005; Schonert-Reichl, 2017). Stress and burnout have been shown to contribute to the attrition of teachers (Darling-Hammond, 2001; Fisher, 2011; Johnson et al., 2005; Klingbeil & Renshaw, 2018; Winchester, 2020). While there are shortages across many disciplines, the bilingual teacher shortage has been documented as the most severe (Swanson & Mason, 2017). This study utilized Community Cultural Wealth as a theoretical framework to investigate how bilingual teacher leaders experience stress …

A Critical Feminist Case Study Of The Northern California Cherry Blossom Queen Program, Alison Kepola Nishiyama-Young

Doctoral Dissertations

Asian American women are chronically underrepresented in leadership positions in almost every sector including higher education, government, private, and non-profit (Youngberg et al., n.d.). Many researchers have suggested the need for more leadership development programs specifically designed to support the needs of Asian American women (Akutagawa, 2014; Canlas, 2016; Gee & Peck, 2015; Lin, 2007; Youngberg et al., n.d.). Though there are a number of leadership programs geared towards Asian Americans, there are very few that cater to Asian American women explicitly. Historically, cultural pageant programs in the Asian American community have played this role and one such program is …

Narratives Of Disability And Displacement: Oral Histories Of The Lived Experiences Of Disabled Refugees, Jennifer Lynn Ward

Doctoral Dissertations

Disabled refugees are considered as the most marginalized group of all displaced populations. Disabled displaced people are at particular risk of violence, exploitation, and abuse. Additional barriers to accessing humanitarian assistance, education, health care, and other services exist for disabled displaced people. The purpose of this study was to collaborate with disabled refugees who have resettled in the United States and to create a space for their stories to be told. This research project explores the narratives of the lived experiences of disabled displaced people through the lenses of three theoretical frameworks: human rights, disability justice, and Critical Refugee Studies. …

Employment Discrimination: An Efficacy Study Of African American Inequities In The California Utility Sector, Victor Baker

Doctoral Dissertations

Employment Discrimination: An Efficacy Study of African American Inequities in the California Utility SectorThe economic legislation of Title VII of the Civil Rights Act of 1964 was designed a vigorous tool of law to address employment discrimination of African Americans and remedy economic disparity that unfavored African Americans. The energy utility industry served as the first Supreme Court defendant and loser of a Title VII employment discrimination challenge by a Black workforce. As a result, energy utility companies have served as the face of resistance to fair employment for African Americans despite the liberal popularity of diversity management programs. Prior …

Replanting A Wild Seed: Black Women School Leaders Subverting Ideological Lynching, Whitneé Louise Garrett-Walker

Doctoral Dissertations

Much race-based educational research is focused on teachers interrupting systems ofoppression in their classrooms, through methods such as curriculum and instruction, and preparing students to engage in the world (Alston, 2012; Bertrand & Rodela, 2017; Carpenter & Diem, 2013; Gooden & Dantley, 2012; Furman, 2012). I intentionally focus my attention on school leadership because while all stakeholders are responsible for maintaining school culture, as school leaders it is our responsibility to create conditions where the work of enacting social justice is expected in our schools. There continues to be a gap in educational research that deeply examines this level of …

Investigating The Self-Efficacy Awareness Of Black Female Technology Leaders, Marie Roberts De La Parra

Doctoral Dissertations

Black female technology leaders lack leadership opportunities, which affects their self-efficacy and is a crucial concern. Self-efficacy is based on the concept that an individual’s belief in what they can achieve influences their actions and how much effort they invest in the selected action. Self-persuasion can provide high or low self-satisfaction as a determinant for creating incentives for success or failure and converting thoughts and emotions to actions. Limited research has investigated the mindset, the thought patterns, and the self-belief undertaken by Black females in the world of technology. Despite limited amounts of research, data suggest that Black female leaders …